What Qualities Make the Best Motor Oil?

Today’s engines are smaller, lighter and produce more horsepower per cubic inch than ever before and yet hold less oil volume, stressing the engines oil to the maximum.

Horsepower increasing additions such as turbo charging and super charging have become common place. Add in ever stricter emissions controls with the stop and go commuting common in today’s congested cities and you have operating conditions that are torturous for your cars motor oil.

So what qualities does motor oil need to have to be able to survive these conditions and still provide proper protection? As they say, “the devil really is in the details” when it comes to a properly formulated motor oil.

We’ll start with issues dealing with viscosity. Good motor oil must be able to maintain a constant viscosity when exposed to temperature changes. It is also very important that the oil be able to maintain its proper viscosity for the entire duration of its intended drain interval.

A oils pour point tells you how well it handles cold is cbd oil legal in canada temperatures without gelling (solidifying). Oils that contain too much paraffin; a wax found in petroleum motor oils tend to gel at low temperatures. Oils with poorly designed additives or low quality viscosity index improvers will also have this problem. Modern engines have tight tolerances’ and need an engine oil to flow quickly at low temperatures to minimize wear at start up.

Tip: Look for oils that have low pour points. The Pour Point Test determines the lowest temperature at which a lubricant flows. The lower a lubricant’s pour point, the better protection it provides in low-temperature service.

At high temperatures and pressures, motor oil must be able to resist shearing forces. The condition known as shear is where the oil is literally torn apart on the molecular level causing it to drop out of its proper viscosity range (example: a 40wt oil shearing into the 30wt range)

This brings us to the subject of volatility and heat related deterioration. At high temperature an oils lighter components can volatilize and boil off. This is especially true of petroleum based motor oils which have a mix of hydrocarbon molecules of various sizes. At high temperatures, the lighter parts boil off leaving the heavier parts. This causes a gradual increase in viscosity and leads to accelerated wear, sludge and engine deposits. The ability to resist shear and volatilizing is particularly important in turbocharged applications where the oil passes through the turbochargers scorching hot bearings.

Full synthetic motor oils made from polyalphaolifin- a manmade engineered molecule, have a uniform molecular structure that is far less volatile at high temperatures making them ideal for high temp/ turbo charged applications.

Volatility is measured using an industry test called the NOACK volatility test and is measure in percentage of weight lost. Good oils will offer 10% or less loss on this test.
Synthetic engine oils will often be less than 8 % loss with some lower than 5%.

Tip: Shear stability testing is done using the ASTM high temperature/high shear stability test (ASTM HT/HS test).
A test result greater than 2.5 is considered very good. Results greater than 3 are exceptional.

Tip: Look for oils with higher flash/fire points. The Flash/Fire Point determines the lowest temperatures at which application of a flame will cause lubricant vapors to ignite (flash point and sustain burning for five seconds (fire point). Lubricants
with higher flash and fire points tend to exhibit more stable volatility characteristics.

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